1979 Volume 13 Issue 3 Pages 153-158
Three species of the genus Glugea (Microsporidea : Nosematidae), G. plecoglossi TAKAHASHI et EGUSA, 1977, G. anomala (MONIEZ, 1887) GURLEY, 1893 and G. hertwigi canadensis FANTHAM et al., 1941, were studied on their spore surface construction and dimentions with a scanning electron microscope. Spores of G. plecoglossi were collected from both fresh and the formalin-preserved Plecoglossus altivelis. Fresh spores of G. anomala from Gasterosteus aculeatus were sent by Dr. J. LOM of the Czechoslovak Academy of Sciences and spores of G. hertwigi canadensis were gathered from a frozen Canadian smelt, Osmerus mordax, imported commercially from Canada. These spores were fixed in 2% glutaraldehyde in 0.1 M phosphate buffer of pH 7.4 for 90 minutes and then in 2% osmium tetraoxide in the same buffer for 60 minutes. After fixation, they were rinsed, dehydrated by passage through a graded series of ethanol, replaced with isoamyl acetate, dried with a critical point dryer, coated with golden ion and examined with the Hitachi MSM-6 at accelrating voltages of 25kV.
G. plecoglossi spores have the smooth surface, though an exception with a fine wrinkle-like structure was found in the formalin-preserved specimens. The treated fresh spores of G. plecoglossi measured 3.9-5.1μm long by 1.7-2.1μm wide, being a little smaller than the figures of 5.1-6.2μm long by 2.0-2.5μm wide reported on the basis of optical microscopic observations. The formalin-fixed spores did not shrink through the treatment. Glugea sp. AWAKURA, 1974 from P. altivelis is distinctly different from G. plecoglossi, because, first, the formalin-preserved spores are bigger than those of G. plecoglossi, being 5.9-6.9 μm long by 2.0-2.4 μm wide according to an optical microscopic observation, and secondly, they have dense fine folds on the surface. G. anomala spores were characterized by the highly rugose surface with a winding longitudinal ridge. G. hertwigi canadensis spores had the rough surface with loose folds and distinct or obscure longitudinal wrinkles which was slightly different from that of G. hertwigi reported by LOM and WEISER in 1972.
